A multicenter, randomized, double-blind, placebo-controlled study of enzastaurin for the prevention of arterial events in patients with vascular Ehlers-Danlos Syndrome (vEDS) confirmed with COL3A1 mutations, followed by an open label extension (OLE)

vEDS is an autosomal-dominant inherited connective tissue disorder caused by
heterozygous mutations in the COL3A1 gene, which encodes the pro-α 1 chain of
collagen III. vEDS is a sub-type of Ehlers-Danlos Syndrome (EDS). vEDS is a
rare disease, with a prevalence of 1 in 50,000 to 1 in 200,000 (Byers et al,
2017). Initial diagnosis depends on the recognitions of clinical features
(thin, translucent skin, easy bruising, and a characteristic facial appearance)
including family history. Most critically, patients are at risk for spontaneous
rupture of the major arteries, hollow organs, and gravid uterus. About 25% of
patients have a first complication by the age of 20 and more than 80% have at
least one complication by the age of 40 (Pepin et al, 2000). The life span for
affected individuals is a median age of about 51 years (49 for males and 53 for
females) (Pepin et al, 2014; Frank et al, 2019). There are no currently
approved therapies, and management is complex and requires multiple specialists
who can respond to and manage the major vascular complications. Various
antihypertensive agents may be prescribed.
Two mouse models were created for vEDS that carry heterozygous mutations in
COL3A1 that encode glycine substitutions analogous to those found in humans
with vEDS and showed that signaling abnormalities in the phospholipase
C/inositol 1,4,5-triphosphate/protein kinase
C/extracellular signal-regulated kinase pathway (PLC/IP3/PKC/ERK) are major
mediators of
vascular pathology. Treatment with pharmacologic inhibitors of ERK1/2 or PKCβ
prevented death due to spontaneous aortic rupture (Bowen et al, 2020). The
results provide evidence that targetable signaling abnormalities contribute to
the pathogenesis of vEDS, highlighting unanticipated therapeutic opportunities.
Enzastaurin is an orally available investigational first-in-class small
molecule, serine/threonine kinase inhibitor of the PKCβ, phosphoinositide
3-kinase (PI3K) and protein kinase B (AKT) pathways.
In the murine model, pharmacologic inhibition using a specific PKCβ inhibitor,
enzastaurin
(60 mg/kg/d), reduced the risk of death from aortic dissection by 60%, with 80%
of enzastaurin treated vEDS mice surviving after 40 days of treatment compared
to only 50% of untreated vEDS mice (p = 0.0305) (WO2020/081741). Further
elucidating that aberrant cellular signaling is the driver of disease,
phosphorylated PKCβ was found in two human vascular tissue samples of patients
who died from genetically confirmed vEDS.

The aim of this study is to evaluate the efficacy, safety, and pharmacokinetics
(PK) of enzastaurin in preventing new arterial events (rupture, dissection,
pseudoaneurysm, carotid-cavernous sinus fistula, or aneurysm, fatal or not)
leading to intervention or mortality attributable to arterial events in
patients with vEDS confirmed with pathogenic variant of COL3A1 gene mutations,
compared to placebo. As adjudication will be performed independently by an
Event Committee, intervention is denoted as (i) emergent hospitalization for
management of an arterial event (ii) surgery for repair (to include
catheter-based procedures), and (iii) symptom-based investigations where
intervention is potentially indicated but the risk of intervention exceeds the
risk of the disease thus precipitating no intervention.

4.1 Overall Design (page 35 PA3)
This is a multicenter, randomized, double-blind, placebo-controlled study with
patients with vEDS receiving enzastaurin 500 mg QD compared to placebo, in
addition to background standard of care, followed by an open label extension
(OLE) phase.
The study will consist of two arms and patients with vEDS will be randomized in
a 1:1 ratio to receive 500 mg enzastaurin QD plus background standard of care
or matching placebo QD plus background standard of care for up to 30 months.
The study will also include a 6 month OLE phase. The objectives and endpoints
will be to evaluate the ongoing efficacy of enzastaurin compared to placebo in
preventing new arterial events (rupture, dissection, pseudoaneurysm, carotid
cavernous sinus fistula or aneurysm) leading to intervention or mortality
attributable to an arterial event, time to intervention for repair of an
arterial event, reduction in rates of intestinal rupture, pneumothorax, and
retinal detachment as well as evaluation of the safety and tolerability of
enzastaurin.
Approximately 220 to 240 adult patients with vEDS are planned to be randomized
in a 1:1 ratio of enzastaurin or placebo, and approximately 20 to 40 adolescent
patients with vEDS are planned to be randomized in a 1:1 ratio of enzastaurin
or placebo. Patients with vEDS will be enrolled in the trial if they meet the
inclusion criteria consisting of age between 18-60 years (for adults) and 12 17
years (adolescent patients) at the time of pivotal study start.
As part of the assessment of inclusion and exclusion criteria, all COL3A1
genetic variants will be reviewed by the Genetic Variant Adjudication
Committee. The diagnosis of vEDS, and inclusion in the study, rests on the
identification of a pathogenic variant in one allele of COL3A1 that is shown or
predicted to result in production of an abnormal protein. Individuals with
these *dominant-negative* variants tend to have more severe clinical
presentations of vEDS. This is the most common class of variants that causes
vEDS and includes: (i) Missense variants that result in substitution of
glycines at the +1 position in the Gly-Xaa-Yaa repeat of the triple helical
domain of COL3A1; (ii) Splice site variants (excluding G>A at the -1 position);
and (iii) In-frame insertions or deletions. Individuals with reduced amount of
COL3A1 protein that results from *haploinsufficient* alleles tend to have
milder clinical presentations of vEDS and are excluded from this study because
these patients are at a reduced risk of arterial events. The use of
anti-hypertensive medications and other chronic care medications such as
vitamin C will be allowed as long as there are no specific contraindications
with enzastaurin.
Patients with vEDS will be ineligible for the study if they are pregnant, are a
woman of childbearing potential on inadequate contraception, or have
contraindications related specifically to enzastaurin or PKC isoform inhibitor.
At the time of interim analysis, safety findings in adults will be utilized to
inform the beginning of enrollment of adolescent patients.
Over the course of the up to 30-month study duration in the double-blind phase,
visits will take place at baseline (Day 1), Day 15, Month 3, and then every 3
months thereafter up to EOS visit at Month 30; vascular imaging will be
conducted at baseline and every 12 months. Periodic imaging analysis will be
conducted via magnetic resonance angiography (MRA) to potentially include use
of intravenous contrast. If contraindicated, then computed tomography (CT) scan
can be utilized and potentially supplemented with ultrasound for selected
arterial segments. For each patient, the same imaging modality will be used
throughout the study. Standardized telephone or videoconference interviews may
also be performed at interim timepoints. Data will be collected to allow for
analysis including number of patients with an event, time to event, and total
number of events for rate calculations.
An electrocardiogram (ECG) monitoring protocol will be utilized to exclude
patients with a prolonged QT interval corrected for heart rate (QTc), and will
consist of ECGs at baseline, 4 to 6 hours post-dose at Day 1, pre dose after
steady state concentrations are reached (Day 15 [Month 0.5]), 4 to 6 hours
post-dose at every visit to include Months 3, 6, 12, 18, 24, and 30. Upon
completion, patients will be automatically rolled over in the OLE phase part of
the study.
The OLE will be a single arm of patients treated with 500 mg enzastaurin QD
starting at Month 30 and continuing for up to 6 months. Over the course of the
6-month OLE phase, visits will take place at the OLE baseline and at Month 6.
At both visits, a full physical examination, drug monitoring, and events
recorded during standardized questionnaires. Standardized telephone or
videoconference interviews may also be performed at interim dates. Data will be
collected to allow for analysis of efficacy as well as safety and tolerability
endpoints.
An overview of study design is provided in the study schema (Section 1.2) and
assessments to be performed in the study are provided in the SoA (Table 1 1).

• Enzastaurin: 500 mg QD orally in the form of four 125 mg tablets with
background standard of care
• Matching placebo with background standard of care

The study lasts 30 months
Blood samples and urine release
Risks of the procedures
Side effects of the medication